Análise de microplásticos na água da chuva no município de Humaitá-AM

Abstract

The increased production and improper disposal of plastics has generated concerns regarding environmental pollution, especially with the emergence of microplastics (MPs), plastic particles smaller than 5 mm. These contaminants are widely distributed in various environmental compartments, including the atmosphere, being transported and deposited by rain. In the Amazonian context, where rainfall patterns play a crucial role in maintaining ecosystems, the identification of MPs in rainwater is still poorly explored. This study aimed to identify the presence of microplastics in rainwater collected in urban and rural areas of the municipality of Humaitá, Amazonas, as well as to characterize these particles in terms of shape, color, size, and polymeric composition. Samples were collected during two precipitation events using Ville de Paris rain gauges. After filtration, the samples were subjected to digestion of organic matter with hydrogen peroxide (H₂O₂ 35%) and separation by density with sodium iodide (NaI) solution. Chemical identification was performed using Fourier transform infrared spectroscopy (μFTIR), with spectral comparison using Open Specy software. A total of 131 particles with characteristics compatible with microplastics were identified, predominantly fibers, white/transparent particles, and sizes between 100 and 500 µm. Chemical characterization confirmed the presence of polypropylene (PP), polyethylene terephthalate (PET), polyester (PES), and polystyrene (PS) polymers, with PP being the most frequent polymer. Microplastics were identified in both urban and rural areas, indicating that atmospheric deposition occurs independently of the degree of urbanization. The results demonstrate that atmospheric precipitation acts as an important transport and deposition pathway for these contaminants in the Amazon region, contributing to a broader understanding of atmospheric microplastic contamination and providing support for future research and environmental monitoring actions.